Case C-194/20: Judgment of the Court (Sixth Chamber) of 3 June 2021 (request for a preliminary ruling from the Verwaltungsgericht Düsseldorf — Germany) — BY, CX, FU, DW, EV v Stadt Duisburg (Reference for a preliminary ruling — EEC-Turkey Association Agreement — Decision No 1/80 — Articles 6 and 7 — Legal employment — Article 9 — Access to education for children of a Turkish worker — Right of residence — Refusal)